Lisa Ramm

Impact of Macular Pigment on Fundus Autofluorescence Lifetimes.

PURPOSE To characterize the macular region and to investigate the influence of the macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo. METHODS Forty-eight healthy subjects with a mean age of 24.1 ± 3.6 years (range, 20-37 years) were included. A 30° retinal field was investigated using the fluorescence lifetime imaging ophthalmoscope (FLIO), based on a Heidelberg Engineering Spectralis system, detecting FAF decays in a short (498-560 nm; ch1)- and a long (560-720 nm; ch2)-wavelength channel. The mean fluorescence lifetime τm was calculated from a 3-exponential approximation of the FAF decays. Macular pigment optical density (MPOD) was measured by one-wavelength reflectometry, and macular optical coherence tomogram (OCT) scans were recorded. Correlations between τm and MPOD were analyzed. RESULTS The τm showed shortest values at the macular region with a mean of 82 ps (ch1) and 126 ps (ch2). We found a strong correlation of τm to the MPOD (ch1: r = -0.760; ch2: r = -0.663; P < 0.001), as well as a topologic agreement of shortest τm with highest MPOD. CONCLUSIONS Macular pigment, which is known to have very short fluorescence decays, considerably contributes to the macular autofluorescence (AF). This study gives indirect evidence for a strong impact of MP on macular τm, although no direct measurement of MP autofluorescence lifetimes in vivo is possible at this point. Potentially, imaging the FAF lifetimes could lead to a novel methodology for the detection of macular pigment properties and pathology-induced changes in the living human retina.

Monitoring macular pigment changes in macular holes using fluorescence lifetime imaging ophthalmoscopy

To investigate the impact of macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo by characterizing full‐thickness idiopathic macular holes (MH) and macular pseudo‐holes (MPH).

Dependence of diameters and oxygen saturation of retinal vessels on visual field damage and age in primary open-angle glaucoma

To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open‐angle glaucoma (POAG).

Monitoring foveal sparing in geographic atrophy with fluorescence lifetime imaging ophthalmoscopy – a novel approach

To investigate fundus autofluorescence (FAF) lifetimes in geographic atrophy (GA) with a focus on macular pigment (MP) and foveal sparing.

Venous retinal oxygen saturation is independent from nerve fibre layer thickness in glaucoma patients

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Measurement of Orbital Biomechanical Properties in Patients with Thyroid Orbitopathy Using the Dynamic Scheimpflug Analyzer (Corvis ST)

ABSTRACT Purpose: To investigate orbital biomechanical properties in patients with thyroid orbitopathy and in age- and gender-matched healthy subjects using the Corvis-ST (CST, Oculus Wetzlar, Germany). Methods: The CST allows a non-contact tonometry with an ultra-high-speed Scheimpflug device to record the deformation of the cornea during an air pulse. Biomechanical response parameters (intraocular pressure (IOP), whole eye movement length (WEMl) and time (WEMt), deflection amplitude 2 mm ratio max, deflection amplitude max, stiffness parameter, and biomechanically corrected IOP were measured in 39 patients with thyroid orbitopathy (= group I) and in 33 age- and gender-matched healthy subjects (= group II) using the CST. Results: Mean age in group I was 54.3 ± 11.6 years and in group II 54.2 ± 12.3 years with no statistical significant difference between the groups (P = 0.98). The gender distribution between the groups was not statistically significantly different (P = 0.51). Mean central corneal thickness was 571 ± 30 µm in group I and 563 ± 36 µm in group II (P = 0.306). There were statistically significant differences (P < 0.001) between groups I and II in mean IOP (19.3 ± 4.5 vs. 14.8 ± 2.3 mmHg, mean biomechanically corrected IOP (17.1 ± 3.4 vs. 13.4 ± 2.1 mmHg), mean WEMl (207 ± 57 vs. 322 ± 50 µm), mean WEMt (20.5 ± 1.0 vs. 21.9 ± 0.7 ms), mean IOP-adjusted WEMl (213 ± 56 vs. 314 ± 62 µm), and in mean stiffness parameter (132.5 ± 29.6 vs. 107.8 ± 23.3 mmHg/mm), respectively. Conclusion: Biomechanical parameters as measured by the CST were significantly reduced in patients with thyroid orbitopathy compared to age- and gender-matched healthy subjects, indicating a reduction in orbital compliance in thyroid orbitopathy. The parameters WEMl and WEMt might be a useful diagnostic tool to evaluate the condition of the eyeball within the orbit.

Assessment of Optic Nerve Head Pallor in Primary Open-Angle Glaucoma Patients and Healthy Subjects

ABSTRACT Purpose: To investigate optic nerve head (ONH) pallor quantitatively in patients with primary open-angle glaucoma (POAG) and in healthy subjects, and to examine the relationship to mean deviation in perimetry (MD), cup-disk ratio (CDR), and diameters of retinal vessels. Methods: A total of 89 POAG patients (67.6 ± 11.1 years) and 48 healthy subjects (63.3 ± 14 years) were included. A dual-bandpass transmission filter was introduced in the illumination path of the fundus camera of the Dynamic Vessel Analyzer (Imedos Systems UG) and two monochromatic images at different wavelenghts (548 ± 10 and 610 ± 10 nm) were recorded simultaneously. ONH pallor was defined as the quotient of light reflection in both spectral channels. Pallor values were averaged over four fields which were positioned on the ONH. The mean of these measurements was calculated. In 47 of 89 POAG patients diameters of retinal vessels were determined peripapillary. Results: In POAG, the ONH showed a significantly higher pallor value compared to healthy subjects (82.34 ± 19.28 vs. 62.67 ± 10.41, p < 0.001). ONH pallor was correlated to indicators used to estimate disease severity: MD (r = −0.565, p < 0.001) and CDR (r = 0.561, p < 0.001). The pallor value was associated to diameters of retinal arterioles (r = −0.313, p = 0.032) and venules (r = −0.397, p = 0.006). Conclusions: Pallor determined by this method was higher in POAG patients than in healthy subjects and increased in patients with advanced disease. ONH pallor might result from a reduced blood perfusion of the ONH or tissue atrophy accompanied by vessel obliteration in POAG. By measuring ONH pallor additional diagnostic information about the vitality of the neuroretinal rim might be gained in glaucoma patients.

The short-term effect of acupuncture on different ocular blood flow parameters in patients with primary open-angle glaucoma: a randomized, clinical study

Introduction To investigate the effect of acupuncture on different ocular blood flow (OBF) parameters in patients with primary open-angle glaucoma (POAG). Patients and methods In a prospective, randomized study, 56 POAG patients were randomly assigned either to an eye-specific acupuncture (group I, n=28) or to an eye-unspecific acupuncture treatment (group II, n=28). Blood flow parameters were measured before and 10 minutes after treatment. Parapapillary retinal blood flow was determined by the Heidelberg retina flowmeter. Retinal vessel diameters were measured by the dynamic vessel analyzer. Pulsatile ocular blood flow, ocular pulse amplitude, and IOP were investigated by the Langham OBF system. Systemic blood pressure was obtained additionally. Results Pulsatile ocular blood flow increased significantly after the eye-specific acupuncture treatment from 5.6±4.3 to 6.7±4.9 µL/min (P=0.014). There was no significant change in parapapillary retinal blood flow, retinal vessel diameter, systemic blood pressure, or IOP after treatment in neither of the two groups. Conclusion An eye-specific acupuncture treatment may affect OBF in POAG patients.

Retinal oxgen metabolism under visual stimulation of neuronal activity in health and disease

Goal: To measure retinal vessel oxygen saturation in rest and under stimulation of neuronal activity by flicker light as well as vascular dilation upon flicker. Methods: 18 patients with non‐proliferative diabetic retinopathy (mean age: 62.2±8.3 years), 41 patients with primary open angle glaucoma (64.0+12.8 years) and 40 control subjects (63.6+14 years) were investigated. Vessel diameters (central retinal arterial and venous equivalents – CRAE and CRVE) and oxygen saturation (SO2, dual – wavelength optical oximetry) were determined before and during luminance flicker stimulation (12.5 Hz, modulation depth: 1:20) for 90 s. Results: Flicker light increased CRAE, CRVE, and venous SO2 by 1.42%±3.72%, 2.80%*±2.70%, and 2.03%*±2.43% in diabetic patients as well as 4.98%*±6.23%, 8.94%*±5.26%, and 4.20%*±3.71% in the controls (*: p<0.05). This increase was significantly higher in the controls vs. patients for all parameters (t‐test, p<0.05. In glaucoma, the increase of CRVE (3.7+3.3%, p=0.039) and venous SO2 (2.482+2.453%, p=0.029) was significantly lower than in controls. Conclusions: Combining SO2 and vessel diameter measurements with visual stimulation reveals pathologic alterations in retinal oxygen supply or consumption.